Pressure ulcers can develop in a person who is bedridden, confined to a wheelchair, or otherwise subject to extended periods of immobility. An estimated 1.3 to 3 million patients in the United States have pressure ulcers; incidence is highest in older patients, especially when hospitalized or in long-term care facilities. Both intrinsic and extrinsic factors may be involved in the development of such pressure ulcers. Aging increases risk, in part because of reduced subcutaneous fat and decreased capillary blood flow. Some additional intrinsic factors include impaired mobility, incontinence, skin condition, nutrition, and altered mental status.
Exposure to pressure is one extrinsic factor. When a bony prominence is pressed against a support surface of a bed or a chair under the person's weight, pressure tends to be focused on that prominence. Depending on the type of mattress or cushion, continuous pressure due to immobility can be at least one contributing factor in causing a break in the person's skin, reduced blood flow to that tissue and/or the loss of surface tissue and disintegration and necrosis of epithelial tissue, i.e., an ulcer.
The scope and cost of such pressure ulcers in the United States are significant. Furthermore, no dollar amount can be placed on the cost of human suffering from this debilitating condition.
Implementation of guidelines set forth by the Agency for Health Care Policy and Research (AHCPR) has produced improvements in carefully monitored institutions. These studies demonstrated that with diligent nursing care, many pressure ulcers are preventable. However, with staff/patient ratios typically found in many health care facilities, it may be impractical to expect all aspects of the AHCPR guidelines to be followed for all but high-risk patients. The extent of this problem can only be expected to grow as medical advances prolong the life expectancy of seriously ill patients and as the population over the age of 65 expands.
Medical conditions that do not necessarily involve immobility can also increase the risk of the formation of pressure ulcers or similar types of sores. These sores typically occur in the lower extremities, such as neuropathic ulcers that are frequently associated with diabetes, where sores may form as a result of the patient's reduced sensation and/or circulation in their feet, sometimes leading to amputation of the foot or leg, or even death from infection at the site when a sore goes untreated. Venous ulcers and arterial ulcers can also result from prolonged pressure and ischemia.
Approaches for prevention of pressure sores tend to fall within two broad, but not necessarily mutually exclusive, categories—underpads, pressure redistribution surfaces and electronic sensors and monitoring systems. Among pressure redistribution or support surfaces, proposed solutions include overlays, replacement mattresses, and specialty beds that attempt to reduce the amount of pressure to which tissues are subjected. These approaches tend to vary in effectiveness, practicality of use, economy and maintenance requirements. Most address a few of the problems, but none considers all of the conditions that can be encountered in patient care including shear forces, moisture management, bunching, surface texture, breathability, odor control, durability and launderability.
Current products tend to focus on single-problem solutions, such as absorbent incontinence pads for handling moisture, or pressure re-distribution surfaces to reduce pressure. In order to avoid ruining a mattress or seat cushion, incontinence pads are often backed with non-breathable waterproof material, so that moisture is trapped within the pad. These pads frequently have cotton or synthetic covers and generally do not have moisture-wicking capability, increasing the risk of ulcer formation in an at-risk patient if the pad is not changed promptly when wet. The current industry approach for dealing with the shearing problem is to coat the top layer of the pad with silicone.
A number have support surface improvements have been suggested for reducing the risk of formation of pressure ulcers. U.S. Patent Publication No. 2007/0277282 of Sheppell, entitled “Support for Prevention of Decubitus Ulcers”, describes a two-layer pad that is attached at selected portions of the fabric to allow parallel movement between the layers to absorb shearing forces. Examples of the layers are spandex for the top layer and nylon for the second layer. The second layer may also be cotton, wool, felt or any of a number of synthetic or blended fabrics. While shearing forces may be reduced, relative movement among the layers raises the opportunity for bunching, which can create lumps that increase pressure against the skin. Furthermore, there is no provision for drawing and keeping moisture away from the skin. The lack of breathability causes skin warming, which contributes to maceration of the skin.
U.S. Patent Publication No. 2007/0261548 Of Vrzalik, assigned to Kinetic Concepts, Inc., describes a multi-layered support system for prevention of decubitus ulcers which has three layers: a vapor permeable layer, a spacer layer having small air pockets through which air can be pumped, and a third outer layer that is vapor and air impermeable. An aperture is formed through one of the outer layers for connection to an air source. The spacer layer can be open cell foam, polymer particles or similar materials. Layers are bonded together using RF welding, heat sealing, or sonic welding. While the contact layer is vapor permeable, there is nothing to keep the moisture away from the skin, and the outer layer prevents evaporation, so that moisture can be retained within the pad.
U.S. Pat. No. 4,962,769 of Garcia, assigned to Prevent Products, describes a three-layer structure that can be used in diapers for bedridden patients. The inner, skin contact layer is water absorbent. The middle layer provides cushioning in the form of patterns of bubbles, similar to bubble wrap and is mostly water impervious except for bores that allow water to pass through. The outer layer is water impervious. The lack of breathability increases the risk of skin warming.
Other proposed approaches include U.S. Pat. No. 7,211,709 of Shimoe, which describes a multi-layered disposable diaper, and U.S. Patent Publication No. 2007/0056096 of Assink, which describes a multi-layer bed pad which includes an upper layer made from very fine, non-woven polyethylene fibers to provide a smooth, low friction surface. This approach also suffers from non-breathable outer layer.
The second approach to reducing the risk of pressure ulcers is to provide a series of electronic sensors that detect pressure and/or moisture on the patient's body, providing input to a computer monitor which may be used to predict risk conditions or generate alarms based on a patient's history of ulcer development, warning a caregiver that the patient needs to be turned or otherwise attended to. U.S. Pat. No. 6,287,253 of Ortega, assigned to Sabolich Research and Development, describes a computer-implemented pressure ulcer management method that applies electronic pressure sensors directly to locations of a patient's body that are at risk for sores, providing read-outs from the sensors to a computer monitoring system, and generating a signal to indicate when attention is required. U.S. Patent Publication No. 2006/0065060 of Ito, assigned to Pentax Corporation describes a multi-layer mat with an embedded array of electronic pressure sensors for detection of pressure and generation of an alarm to indicate when abnormal pressure is present, notifying the caregiver that a patient needs to be turned to prevent formation of pressure sores. Such systems can be quite costly and generally will be purchased for institutional usage more so that for in home use.
In view of the foregoing, and as an increased number of patients are given home care, there is the need for effective and affordable materials and devices for pressure ulcer management and prevention.